Oswan

This is a very nice and fast WonderSwan emulator, this baby emulates color and mono games, it has a good CPU timing, the sound is really good and it supports Joystick.
It is based off the Cygne source code.
The GUI:
To access the GUI while playing a game, press ESC key.
The keys are:
- Arrows for movement
- X for button A
- C for button B